Simulation analysis of lift off on an eddy current sensor array's output characteristics based on finite element method

A finite element model of an eddy current sensor array is built up by electromagnetic-circuit couple method, and the influences of lift off on sensor's output characteristics are analyzed by this model. There would be a change on amplitude and phase when lift off distance is altered, and the amplitude and phase of sensor coil are increasing gradually as lift off distance increased. When lift off distance increased, the increase of amplitude and phase of sensor decrease gradually. Besides, the relationship between left off distance and sensor's output is established by nonlinear fitting, and it would provide a reference in further lift off or corrosion inspection.